#include <iostream>
#include <string>
using namespace std;

void _cal()
{
#include <typeinfo>

    int a = 1;
    double b = 2.1;
    cout << "before a *= b, \t\ttype a is " << typeid(a).name() << a << endl;
    a *= b;
    cout << "after a *= b, \t\ttype a is " << typeid(a).name() << a << endl;
    a *= static_cast<int>(b);
    cout << "after a *= static_cast<int>(b), \t\ttype a is " << typeid(a).name() << a << endl;
}

int main()
{
    _cal();
    return 0;
}